Avaliação de processos ecológicos de riachos em zonas ripárias da Floresta Atlântica

Abstract

There is evidence that the entry of Eucalyptus leaves into streams can cause changes in ecosystem processes, such as leaf decomposition, for example. However, it is not clear how eucalyptus leaves relate to native plant species, and how they interfere with communities, and the characteristics of streams. In addition, as the loss of diversity of native plant species, associated with the presence of eucalyptus, would affect the decomposition process in streams. To answer these questions we have created two chapters. Chapter 1, The influence of detritus quality on leaf decomposition of streams in the Atlantic Forest. In this study we evaluated how the total and microorganism decomposition reacts to changes in the quality of debris and the type of stream. We tested the hypothesis that the quality of the detritus controls the rate of total leaf decomposition and by microorganisms, regardless of the characteristics of streams. Chapter 2. Effect of loss of plant species diversity on the decomposition and production of fine particulate organic material (FPOM) by larvae of Phylloicus sp. (Trichoptera: Calamoceratidae); we evaluated using a microcosm experiment with three species of native plants (Alchornea triplinervia, Licania tomentosa, Magnolia ovata) and an exotic hybrid species found in the region (Eucalyptus urograndis). We hypothesized that the loss of plant diversity would lead to decreased decomposition and production of FPOM, but the magnitude of this effect would vary depending on the chemical and hardness characteristics of the component species. We found in Chapter 1, that the (I) type of leaves present in streams interferes with the results of the decomposition rate in the coarse and fine mesh; (II) and most of the differences are associated with the chemical and structural characteristics of the species; (III) that differences between streams were reflected only in the decomposition of the coarse mesh. In chapter 2, we found that the leaves of E. urograndis may be attractive resources for the larvae of Phylloicus sp., And that their consumption did not result in losses in the larvae survival. In addition, the leaf species with the highest rate of decomposition and production of FPOM by Phylloicus sp. it was A. triplinervia, and the consumption of E. urograndis did not differ from the other species, but it provided the lowest production of FPOM. The loss of diversity of plant species can result in a decrease in the rate of decomposition by microorganisms, but it did not interfere in the rate of decomposition in the presence of Phylloicus sp. and in the production of FPOM. Changes in the diversity of leaf species did not result in negative effects on the survival of Phylloicus sp